OpenAra defines 9 computer-use tools with complete input schemas and descriptions. All tools follow a clear verb_noun naming convention (list_apps, get_app_state, click, etc.) and include structured schemas with property types. Descriptions are clear and specify the tool's purpose. However, there are moderate gaps: (1) Output schemas are not documented, the source shows input schemas but no structured return types, forcing LLMs to infer response format. (2) Error handling is minimal, no error classification, recovery guidance, or constraint violation messaging. (3) Parameters lack granular constraint documentation (e.g., 'direction' in scroll_tool lists valid values in description but not as enum). (4) No documentation of parameter dependencies or mutually exclusive patterns (e.g., click accepts both element_index and x/y coordinates, which takes precedence?). (5) Descriptions are functional but minimal (averaging ~120 chars), many lack hints about when to use the tool vs. related ones. These gaps are typical for domain-specific tools but reduce LLM planning efficiency.

• Document output schemas for all 9 tools. For example, 'list_apps' should specify that it returns {apps: [{name: string, bundle_id: string, running: boolean, last_used: ISO8601_date, usage_frequency: enum}]}. Make return types explicit so LLMs can plan downstream calls.
• Formalize all parameter constraints as JSON Schema enums/patterns. Convert 'direction: up, down, left, or right' to enum: [up, down, left, right]. Convert app name/bundle examples into minLength/pattern constraints.
• Clarify 'click' tool semantics: document that element_index and x/y are alternative inputs, not simultaneous. State which parameter takes precedence. Mark one as required and others as optional, or split into separate tools (click_element vs click_coordinates).
• Expand tool descriptions to 150-250 characters each, following the pattern: WHAT it does + WHEN to use it + prerequisites. Example: 'Click an element in the active app window. Call this after get_app_state() to interact with UI. Pass either element_index (from accessibility tree) or x/y pixel coordinates (from screenshot).'
• Add per-parameter validation rules in descriptions. E.g., 'app: App name (e.g. Safari, Finder) or bundle identifier (e.g. com.apple.Safari)' and 'element_index: String element identifier from accessibility tree returned by get_app_state().'
• Implement error handling with recovery guidance. Return errors like 'App "InvalidApp" not found. Available apps: [Safari, Finder, Mail]. Try get_app_state() with one of these first.' instead of bare failure codes.